A vast array of electronic circuits have been implemented in the form of integrated circuits utilizing semi-conductor materials. Large numbers of circuit components are integrated upon a single integrated circuit to permit an electronic circuit formed therefrom to be of very small dimensions.
Continued advancements in the field of integrated circuit design have permitted increased miniaturization of the circuit components forming the electronic circuits implemented in integrated circuits.
Circuit elements of an integrated circuit are formed of groups of P-N regions. To facilitate circuit operation, during powering-up, charge pumping of selected portions of such groups of P-N regions is sometimes performed. Charge pumping is a relatively slow process by which to bias a region of an integrated circuit, at least relative to the significantly greater rate at which a fixed power supply can bias a region of an integrated circuit.
The relative time lag of biasing of an integrated circuit region by charge pumping relative to the application of another region of the integrated circuit with a fixed power supply can lead to a problem referred to as "latch-up". Injection of currents into an integrated circuit coupled to be biased both by a fixed supply and by charge pumping can instigate the occurrence of latch-up of the circuit device.
U.S. Pat. No. 5,321,324, assigned to the assignee of the present invention, discloses, inter alia, a voltage translator with latch-up immunity. Current injection which might otherwise instigate latch-up of the voltage translator disclosed therein is prevented until the charge-pumped regions of the integrated circuit forming the voltage translator are of levels great enough such that latch-up of the translator shall not occur.
A voltage translator translates the voltage levels of an input signal into a translated voltage level to form a translated signal of a translated voltage level. A voltage translator is utilized, for instance, in an electronic circuit which has both low and high voltage requirements. A DRAM (dynamic random access memory) is exemplary of an electronic circuit which has both low and high voltage requirements. Low voltages are required for normal operation of the DRAM, whereas the higher voltages may be used to write, restore, or refresh a high-voltage value stored in a memory cell. Translated voltages may also be utilized to form other signals, such as control signals utilized during operation of such a circuit.
Other electronic circuits embodied in integrated circuit devices in which charge pumping is utilized are similarly susceptible to the occurrence of latch-up. A manner by which to prevent latch-up is necessary to ensure proper functioning of the electronic circuit and to prevent damage to the circuit.
While the latch-up immunity provided to the voltage translator disclosed in the aforementioned U.S. Pat. No. 5,321,324 prevents the occurrence of latch-up, such protection is provided through the use of a plurality of circuit elements. And, when the injection of the current is permitted, once the charge pumping biases the integrated circuit regions to an appropriate level, the signal permitted to be applied to the voltage translator is inverted.
Any manner by which to reduce the number of circuit elements required to prevent the occurrence of latch-up would advantageously facilitate the reduction in chip-space required to implement an electronic circuit including circuitry for preventing circuit latch-up.
A manner by which to permit the injection of current to the electronic circuit when such injection would not instigate the occurrence of latch-up without inverting the current signal, would also be advantageous.
It is in light of this background information related to integrated circuit devices that the significant advantages of the present invention have evolved.